Chemical surface treatment of ferrous bearing metals



Patented Jan. 3,1950

CHEMICAL SURFACE TREATMENT OF Y FERROUS )BEARING yMIE TALS 30h11 C. Zimmer, Union,

to Standard OilDevelo prat'ibndfnelawer e No brewing. 'orf 1942, vSerial No.

Aand Arnold J. Morway, Uifointy,

pnrent Company, a cor- N. J., assgnors giial--aiipli'cation December 19, 469,512. Divided and this application October 15, 1946, Serial No. 703,277

. ,1 "iiis invention fentes to imprsvea e-"aepme pressure `rubbing surfaces. It fis concerned iii/ith the improvement `of ferrous gears or `oth"er ferlfr iris bearing "elements which are subjected "-to :hgh'pr'e'ss'ures for example, ferrous Lgea'rs of the 'hypoid `or similar type. The invention especially relates :t'o the improvement Lof rubbing surfaces 'secured by Va chemical pretreatment -of the A'said straws.

This J`ja'ppli 'c'ati'on is 'a "division'oi'ourcpendig application senai Number `469,512, niet vDecem- 'ber -19, 1942, now-abandoned, 'vvin'cilfis ca continqnli'ri'paijt -of application serial' Number *1172928, yme@December 3, '71937, new #Patent No. 2,310,381, granted February 9, 194;

The present A invention is tobe distinguished ffbm'tneffnere Cleansing-0f metauien'rfaees with acid inahrung inate'nalsfor fthe f't'reatmen-t' of sur- 'Jfaces ffr lthe prevention of fs'econdary reactions Usu'ch fas oidation 'I'he invention 'secures irn- -'p'rbve'd rubbing f ferrous Isurfaces yby"'ti'featin'g v"the sain surfaces with aeesforboron andthe sans head carrying-atacan aswell 'as reducing aar-- Yas It is well known in the art toimprve theloaii carrying'capa'c'ity of rubbing surfaces, particulalyhypoi'd gearsby'the use of so-called extreme pressure lubricants. |I 'hese eXtreme pres- "30 sure lubricants `are usually lsuliuriz'ed or chlori- 'I hated irmineral nfor rvegetable oils in 'combination failures by seizure of the bearing surfaces. This process has the inherent disadvantages that the plating chips and cracks or Wears ofl rather readily. In addition, particularly in the case with copper plated gears, the metal seems to act as an accelerator for oxidation and thickening of the gear lubricant.

The present invention secures improved load carrying capacity by preactivation of the gears or rubbing surfaces and thereafter permits the use of an ordinary lubricant which would otherwise be entirely unsatisfactory. The process of the present invention may also be used in conjunction with extreme pressure lubricants in order to further increase load carrying 'capacity and minimize bea-ring seizure;

The improved Aferrous rubbing surfaces Aof mafchinegelem'ents jslch 'a'sg'ears bearings, earns, Vvstonjs, cylinders, rings; 'races'. valve dt'helike. jare secured bytreating the rmetal Twith'aisolation contaimngfan anioniof acid of boron', `more vpa'rticilarly an'acid" fboron or a salt thereof. !Iheli-mprovement appears to be secured by the formation of a coating of iron 'b''lat'e lon the metallic surfaces.' -Es'peclallyutable :are the oa-yacias for bo'ron @and aber salts. @referred -rubbinglsdrraees :are fse'curedxly treating thefferrous-'Irnetals Withfanfaqueous-solution r`ofbo'ri'cla'cicl or of alborate,fsuch'faslsodiinn tetraborate, or with an aqueous'isolution a mixture of an acid-of-boron and a salt thereof. Solutions containing f mixtures of an acid lq'uite effective, for example, a l'rn'i'iiture 'of lbbr'ic `lac-idiand phosphoric not-"only improve "the load --carryin'g l'capacity of the surfaces Ibut 'markedly improve "-tliea-ability-'f the surfaces to resistzcorrosion in the presence of moist air.

'Ifhfe markediimprovementsecuredfbythls proc- Less" i' shown by'fthe "following"d'a'ta-l obtained "in "specinc examples winchv serve to illustrate :the

" 'Irivetion "Steel rods ^w`ere treated f in lthe' lmanl"nerf describ'efiajnd thenA were tested onf the Almen machine, "which I"is described infdetail Iin jthe fNationaiTetmieu'm- News,

:November I6; '11932. TheA operation of this machine can be briey suInmari zedI asflol'lows f l i machine'fis lportable and hemploys ia 1A;- inch drill-rod journal -'and 1/geinch"split "bushjournal is polished and ythe bushing'-afterfsplitis provided between the journal and the normal diameter of the bushing. Pressure is applied to the bushing by means of a hydraulic and mechanical loading system. The friction torque developed is indicated through a second hydraulic system by a Bourdon gage.

In conducting -a test the oil container is rst fllled with oil to be tested (about 25 ml.) submerging the test journal. The machine is then started and run for 30 seconds at no load to insure thorough lubrication of the journal and bushing. The load is then applied at the rate of 2 1b. every 10 seconds until seizure occurs or until 30 lb. have been applied. The speed of bearing.

utes.

cation of weights, a bell is provided'and so arrotation is 600 R. P. M. For timingl th applicondensing moisture. The results of the corrosion tests are shown in the following table:

Saturated ranged as to ring at second intervals.l Each Z-lb. weight produces a pressure of approximately 1,000 lb. per sq. in. of projected area on the test EXAMPLE 1 A's'teel rod tested'on the Almen machine `using .an uncompounded A. E. grade carried 3 weights before seizure mineral lubricating oil of S.

occurred. This mineral lubricating oil was used as the lubricantin vExamples 2vv and'3.

EXAMPLE 2 5% boric acid was heated to boiling and the steel rod of the Almen machine immersed in said boiling solution fork about `30 minutes. The rod, upon being dried and tested on the 'Almenrmachine, carried 11 weights.V i

EXAMPLES VAnV aqueous solution containing 2% boric acid `and 0.5% phosphoric'acid was heated toboiling and the steel rod of the `Almen .machine immersed in the boiling solution for about min- This rod, upon being dried and tested in the Almen machine, carried 14 weights.

EXAMPLE 4' A series rous Almen machine journals and bushings after these had been treated with boiling aqueous solutions of various compounds of boron and mixtures of the same for Various periods ofY time.

The corrosion tests were conducted by hanging 4the treated journals and bushings in an insulated humidifier box of approximately 2' x 2l x 4 dimensions, passing in air saturated with moisture at about 140 F. at the rate of about 15 cu. ift. of air Vper hour, the temperature in the interior of the box being about 100 F.v The test'was conducted in each case for 48 hours. The air Within the box under these conditions was therefore vnot only saturated with moisture but containedV of corrosion testswere made onvfer- Y aqueous, solution `containing approximately The operating conditions may be varied over wide limits. The treating operation may be carried out under pressure or vacuum although it is preferred to treat at atmospheric pressure. Thevtemperature of the treating bathvmay be as high as 300 F. although the preferred range is from about F. vto the boiling point of the bath. It is preferred to maintain a temperature a few degreesbelow the boiling point of the respectivebaths. The time of treatmentV is less than about one hour,v preferably from 15 minutes to 30 minutes.A The concentration of inorganic material is maintainedbelow about 20%. Concentrations from 12% to 10% are preferred.

The invention is not to be limited by any theory of operation nor by the examples of Vits embodiment which are described herein, but onlylbyrthe following claim. Y

l Y We claim.:

; In the method of improving load-carrying capacity of the finished .surface of a ferrous-al loy machine element which is to be subjected to extreme pressure rubbingv contact, the-iniprovement consisting in chemically treating said surface with a boiling aqueous solution composed essentially of boric acid of approximately 5% concentration for a time period of from about 15 to 30 minutes, then removing the treated surface and drying the same.

v JOHN C. ZIMMER,

ARNOLD J. ,MORWASYA REFERENCES CITED s The following references are of record in the Yfile of this patent:

UNITED STATES PATENTS Number Name Date 1,610,362 Coslett Dec. 14, 1926 2,311,653 Farrington et al. Feb. 23, 1943 FOREIGN PATENTS Number Country Date `394,132 Germany Apr. 14, 1924 

